In this invention, the polymerization catalysts useful in polymerizing and copolymerizing 1-olefins are prepared by the reaction of silica or alumina with a functional silane compound, organomagnesium compound, an alcohol, and a titanium, vanadium, zirconium or mixture of these compounds. These catalysts are then activated, associating them with an organoaluminum cocatalyst. These catalyst products are primarily useful for the polymerization of 1-olefins such as ethylene and the copolymerization of these 1-olefins.
One of the features of the invention is to provide an improved method of polymerizing with these catalysts in the particle form slurry, gas phase or solution form polymerization processes.
Another feature of the invention is that the polymerization reactions promoted by the improved catalysts are more readily modified by hydrogen so that desirable high melt index polymers are easily made.
A further feature is that the higher melt index polymers so produced are narrow in molecular weight distribution and are therefore highly suitable for injection molding or cast film applications.
Yet another feature of the invention is to provide a catalyst yielding high melt index, high density polyethylene in the particle form process without reactor fouling.
Still another feature of this invention is the production of ethylene-1-alkene copolymers, commonly known as linear low density polyethylene (LLDPE), by the catalyst of this invention. These copolymers can have densities from 0.915 to 0.960 g/cm.sup.3 and properties suitable for film and injection molding applications, for example.
K. Ziegler first discovered two component catalysts based on compounds of the Group IVB-VIB metals of the periodic table and an organometallic compound belonging to Groups I-IIIA of the periodic table for the polymerization of olefins. Since his discovery, numerous catalysts have been disclosed as improvements over the original Ziegler catalysts. Most of these catalyst systems are of relatively low activity and stability. They require a costly catalyst removal step.
One of the modifications attempted in an effort to increase the activity of the Ziegler type catalyst was to deposit the catalyst components on an inert support. In U.S. Pat. No. 2,981,725, such a process is disclosed. The supports used were magnesium chloride, silicon carbide, silica gel, calcium chloride, etc.
The activity of the catalysts disclosed in these patents was still low.
South Africa Appln. No. 69/3534, 10/5/69 by Van Den Berg and Tomiers of Stamicarbon describes catalysts made from organomagnesium compounds, alkyl aluminum chloride compounds, and titanium compounds which are increased in reactivity by the addition of alcohols. A support, or granular ingredient, is not used, there is no separation of the solvent, and the use of a cocatalyst is not disclosed.
German Offen. No. 2,721,058, 11/23/78, by Gunter Schweier et al. of BASF reveals a catalyst with a porous inorganic oxide like silica or silica-alumina as a support. A solution of a reaction mixture of an alcohol, a titanium trihalide, and a magnesium compound is added to the oxide, and then the solvent (i.e. the alcohol) is evaporated giving an intermediate solid product. This solid product is suspended in a solution of an organometallic compound, which may be an alkyl aluminum or silicon halide compound. The suspended solid component may be used as is along with an organometallic compound as a cocatalyst. The suspended solid compound can also be filtered, and washed prior to use, and for gas phase polymerization it can be coated with wax. The magnesium compounds are not alkyl magnesium compounds but alkoxides and halides and other types of compounds.
Another Schweier patent, German Offen. No. 2,721,094 is similar to this one. It reveals that the silica or silica-alumina may be treated with an alkyl aluminum halide compound beforehand.
U.S. Pat. No. 4,110,523, 8/29/78, also by Schweier et al., covers a similar catalyst. In this case, the treatment with the alkyl aluminum or silicon halide solution is eliminated.
U.S. Pat. No. 4,130,699, 12/19/78 by G. R. Hoff and Peter Fotis of Standard Oil Company discloses supported catalysts for vapor phase polymerization which are made less active prior to feeding to the reaction vessel by treatment with alcohols, acetates, ketones, aldehydes, or esters.
U.S. Pat. No. 4,105,585, 8/8/78 by Ian Matheson of BP Chemicals describes catalysts prepared from the reaction of magnesium powder, a titanium halide and alcohol.
U.S. Pat. No. 3,647,772 by N. Kashiwa (Mitsuit Petrochemical, 5/7/72) involves treating anhydrous magnesium carbonate with polar organic compounds including alcohols. When this is done, more titanium from titanium tetrachloride can be fixed upon the magnesium carbonate. Catalyst reactivity, melt index and bulk density of the product are increased by the treatment with the polar organic compound.
None of the above patents disclose the method and products of this invention.